Fish With Fins and Scales

Fish have the most diverse vertebrae of most living things on the planet. The wide variety of these animals makes it necessary to classify them into specific groups. Some fish even lack vertebrae and make way for numerous exceptions when being categorized into groups. Fish can be one of the most exciting animals with their evolving anatomy and variety of functions. Their skeletons classify most fish and seafood, and a common query is raised to determine the kinds of fish that have fins and scales and those which do not. This also holds importance in the Jewish Religion, which highlights the unclean and clean types of fish to eat. Some fish lack common limbs or skeletal parts, yet they still adapt perfectly to their environment. However, most fishes in the food industry are those which possess both fins and scales.

fish anatomy - Fish With Fins and Scales

As we know from biology, fins help the fish swim, while scales cover the body.

Why do fish have scales?

Fish have scales because scales, like a suit of armor, protect the fish’s skin from various attacks from predators and other injuries. Additionally, scales protect fish against infection and parasites.

You can see that some fish have a toxic slime layer that helps during evolution to defend fish against predators.


Does salmon have scales?

Yes, salmon has scales that begin to grow at the fry stage. The salmon’s scales overlap a flexible armor plating at salmons that protect them from bruising and predators.

salmon scales - anatomy

Over the past centuries, all living things have evolved to adapt better to rough environments and climates and fend for predators or prey. Similarly, fish have evolved over the years for the same reason. Considering this, the skeletal composition of a fish is essential to ensure its protection in water bodies from harmful predators, parasites, and physical injury. Fish mainly rely on their skeletal design, as the absence of limbs can make them susceptible to dangerous predators. The main parts of a fish that we learn about are the fins and scales. Regardless of the strength of a fish, fins assist in movement. But alas, all fishes need some form of protection.

Does flounder have scales?

Yes, flounder has scales. The flounder is kosher because it has both fins and scales.

flounder anatomy - flounder scales

This is where we see the role of scales be highlighted as scales were evolved to fulfill the purpose of protection for small or comparatively weak fish against the environment and predators. The scales on a fish are usually complex, and they stretch throughout the body of a fish. This does not necessarily mean that the fish that do not have scales aren’t protected. They have different characteristics that prevent them from facing harm or trouble and adapting to harsh environments. Enhanced sensory organs compensate for the absence of scales in certain fish to protect themselves better.

It is common for us to mistake fish with smooth skin for scaleless fish; however, that is not the case. Most fish have small, thin scales which are near impossible to detect with the naked eye. However, most scaleless fish vary in behavior and morphology. Therefore, these fish are categorized to understand their behaviors better.

Fish without scales

Fish without scales are sharks, catfish, rays, skates, chimeras, moray eels, paddlefishes, sturgeons, combtooth blennies, sailfin blennies, hagfishes, and lampreys.

  • Jawless fish are biologically termed Petromyzontiformes. These comprise lampreys.
  • Chimaeriformes, which are known commonly as “Ratfish.”
  • Anguilliformes, which comprise conger eel and moray eel
  • Siluriformes, also known as catfish
  • Myxiniformes, which are hagfish and agnate fish.
  • Apart from these main categories, we also know Freshwater Blenny, a scaleless fish, swordfish, common sturgeon, and tiger sorubim.


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Does codfish have scales?

Yes, codfish has scales. Codfish is kosher because it has both fins and scales.

codfish anatomy - codfish scales

Do sardines have scales?

Yes, sardines have scales. However, sardines do not have scales on their head. Sardines are small, silvery, elongated fishes with a single short dorsal fin.

sardines scales

Does tilapia have scales?

Yes, tilapia has scales. Tilapia has a long dorsal fin, a lateral line that breaks towards the end of the dorsal fin, and two or three rows of scales below.

tilapia scales

Similarly, fins are an essential part of fish anatomy. They help fish gain momentum and give them a lift, steering, and braking ability. As legs are to humans, fins are to fish. Modern fish have a vast array of fin structures and shapes. Certain fish have no scales, but they have fins. Naturally, a fish is heavier than water and requires fins to stay up. Still, not all fish have fins and those that don’t have developed body parts that help them adapt quickly and are found in habitats made for them. Fish fins generally have seven main types.
In some cases, fishes have an incomplete fin; some have different variations of the same type of fin, for example, a divided dorsal fin and a joint one. The anatomical evolution depends mainly on its habitat and environment and the type of water body it lives in. Widely known fish that have fins but no present scales are called tuna.

Fish with fins and scales

Fish with fins and scales are shrimp/prawns, scallops, lobster, oysters, mussels, octopus, squid, and crabs. Also, shellfish have no vertebrae and are encased in a hard shell. Examples of these are oysters, clams, and mussels. Similarly, shrimps, lobsters, and crabs are known as crustaceans, developed inside a hard outer covering.

However, fish have fins and scales, considered “true fish.” They are also categorized as kosher fish in the Jewish religion and are widely preferred compared to other fishes that lack scales or fins. More kosher fish (scales and fins) are bass, cod, carp, flounder, halibut, herring, trout, mackerel, and salmon.

Does tuna have fins and scales?

Yes, tuna has scales and fins. Tuna is kosher because it has both fins and scales. However, tuna has very few scales.

tuna anatomy - tuna scales and fin

Does halibut have scales?

Yes, halibut have scales. However, halibut have tiny scales that are invisible to the naked eye because scales are embedded in halibut skin.

Other fish that have both fins and scales are grouper fish, tilapia, and red snapper.

Many of these fishes are considered delicacies globally and can make up some of the most expensive dishes. Most fishes require the removal of their scales, so it is easier to eat them. In a religious perspective, particularly Jewish, the fish with fins and scales, a minimum of one of each, are considered clean fish that can be eaten, and the ones with none are considered unclean.

However, regardless of certain skeletal parts in fish, some types of fish can be very harmful to eat, for example, Tilapia, Atlantic Cod, Atlantic Flatfish, and caviar. These are harmful to the consumer, and fish like Beluga sturgeon are almost endangered because their caviar is sought after.

Thus, fish should be carefully dealt with and properly researched to prevent harm from reaching them like all living things. Besides, time makes way for the further evolution of these animals, which can bring forth even more exciting facts about fishes and their ever-changing plethora of skeletal structures.

Igor Milosevic
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